Predictive drive control

ABSTRACT

A drive control illustrated for controlling an elevator hoist motor and car position involving a control pattern causing the car to follow idealized constraints of constant jerk in transitions between constant velocity and constant acceleration. In the initial phase the control pattern for the car is started, from zero velocity, through constant positive jerk to a constant acceleration which, if a run of sufficient length is required, is followed by a constant negative jerk into a maximum constant velocity. The length of the constant acceleration interval is terminated by achieving a predetermined velocity which when subjected to the predetermined negative jerk value will achieve zero acceleration at the given maximum velocity. Deceleration is initiated at the moment the control pattern is indicated to be capable of stopping the car, within the constraints of jerk and negative acceleration, at the desired destination. The instant of initiation of the terminal phase of the pattern is ascertained by a high speed repetitive predicted pattern generated from the control pattern, for example at a speed one thousand times faster than the control pattern and with constraints which make its performance slightly inferior to that of the elevator. The predicted pattern indicates a stop position slightly in advance of the stop achieved by the elevator under the predetermined constraints of the control pattern. During deceleration, the predicted pattern is repetitively generated from the control pattern as an initial point. The indication of a predicted pattern stopping position short of the desired stop causes the control pattern to switch to positive jerk while prediction of a stop beyond the desired stop causes the control pattern to switch to negative jerk. This chattering control brings the elevator to the desired floor in a closed loop control.

United States Patent [191 Gilbert et al.

[ PREDICTIVEDRIVE CONTROL [75 lnventorsi Edward 0. Gilbert; Elmer G.

Gilbert, both of Ann Arbor, Mich.

[73] Assignee: Reliance Electric Company,

Cleveland, Ohio 22 Filed: .May 9,1972

21 Appl. No.: 251,810

[52] US. Cl 187/29 R Primary Examiner-Bernard A. Gilheany Assistant ExaminerW. E. Duncanson, Jr. Attorney-Wilson & Fraser ABSTRACT A drive control illustrated for controlling an elevator hoist motor and car position involving a control pattern causing the car to follow idealized constraints of constant jerk in transitions between constant velocity and constant acceleration. 1n the initial phase the control pattern for the car is started, from zero velocity,

LOGlC GENERATOR SYSTE M CONTROL FLOOR POSITION OF CAR PRIORITY POSITlON BINARY TD DE CODER Jan. 8, 1974 through constant positive jerk to a constant acceleration which, if a run of sufficient length is required, is followed by a constant negative jerk into a maximum constant velocity. The length of the constant acceleration interval is terminated by achieving a predetermined velocity which when subjected to the predetermined negative jerk value will achieve zero acceleration at the given maximum velocity. Deceleration is initiated at the moment the control pattern is indicated to be capable of stopping the car, within the constraints of jerk and negative acceleration, at the desired destination.

The instant of initiation of the terminal phase of the pattern is ascertained by a high speed repetitive predicted pattern generated from the control pattern, for example at a speed one thousand times faster than the control pattern and with constraints which make its performance slightly inferior to that of the elevator. The predicted pattern indicates a stop position slightly in advance of the stop achieved by the elevator under the predetermined constraints of the control pattern. During deceleration, the predicted pattern is repetitively generated from the control pattern as an initial point. The indication of a predicted pattern stoppingposition short of the desired stop causes the control pattern to switch to positive jerk while prediction of a stop beyond the desired stop causes the control pattern to switch to negative jerk. This chattering control brings the elevator to the desired floor in a closed loop control.

81 Claims, 25 Drawing Figures FLOOR LI NES PATENTEII 81974 3.783.974

SHEEI 010T II ELEVATOR VELOCITY VARIABLE ---Il CONTROLLER CONTROL VOLTAGE HOIST -I UNIT l5 DRIVE -I4 MOTUR II A WTS/ CAR POSITION-"CAR I2 TARGET FLOOR VELOCITY /STOP INITIATED VELOCITY A VELOCITY 0 STOP INITIATEO I v E /STOP I h, I, i. h t,-. 5 DISPLACEMENT FIG. 3 FIG. 4

I F FIG. 6A FIG. 68 III iD FIG. 6D :31}

FIG. 61

PRESET PATENTEUJAN 81974 SIIEEI 02 0F 11 LOGIC GENERATOR 45 43 4s 44 FAST D TEE PLANT SYSTEM JERK sLOw TDVELOCITY START coNTROL LOGIC PLANT QR STEP COUNTER 34 32 LATCH 27 42 FLOOR AND D A C c R BINARY DOWN 35 OUNTE l-SUBTRACTER Q II II 5%? PRESP gg; I REQUESL 33 P05 ION 2s FLOOR 23 S 8$B 24 l lTNOE5 25 POSITION PRIORITY OF CAR NES BINARY CAR DECODER POsITION POSITION I r PULSE uP- DOWN DATA Egg? GENERATOR COUNTER SETS CAR PATENTED 8W 3,783.974

sum as or 11 M- 2 32 FIG. 9

ll T040827 FROM 38 74 FROM 38 F ROM 39 l3 TO 7 FIGII PATENTED 974 3.783874 SHEET 08 0F 11 F AL LLD I62 QFR M 43 l m -W PATENIEDJAN M4 WE 09 0F 11 mm 205 wzoE N m hm N MNN N mm EONE 1 PREDICTIVE DRIVE coNrRoL CROSS-REFERENCE TO RELATED APPLICATIONS This invention in one embodiment employs position signals sensed by a digital position sensing scheme as disclosed in the patent application of Edward O. Gilbert, G. D. Robaszkiewicz and George S. Dixon, Jr., entitled Elevator Electronic Position Device, Ser. No. 251,793 filed herewith. It has been utilized with a means of achieving a final registry of the driven object with its stopping point as disclosed in the application of Robert J. Lauer and Joseph Kuhl entitled Final Stopping Control, Ser. No. 251,801 filed herewith.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to controls for driving objects and more particularly to controls-for optimizing the driven motion of an object along a path. In the discussion which follows the object is exemplified as an elevator car movable along a hatchway although other objects or vehicles might be controlled similarly. The control utilizes a pattern signal generator for controlling the drive in conjunction with a predicted pattern signal generator operating at a high rate of repetition to predict the stopping position which could be achieved by the controlling pattern and thus the controlled driven object. Results of the prediction are employed to alter the controlling pattern signal.

2. Description of the Prior Art Heretofore it has been known to control motion of a driven object under constraints of constant jerk, maximum acceleration at a constant value, and maximum velocity at a constant value. Such control optimizes travel time where the transition from-zero velocity to maximum acceleration is accomplished with constant jerk or rate of change of acceleration, maximum acceleration is maintained constant until the velocity approaches its maximum, the transition between maximum acceleration and maximum velocity is with constant jerk, and the transitions to stop from maximum velocity is with constant jerk to maximum negative acceleration or deceleration and from maximum deceleration to zero velocity is with constant jerk. U.S. Pat. No. 3,523,232 which issued Aug. 4, 1970 in the names of Donivan L. Hall, Richard C. Loshbough and Gerald D. Robaszkiewicz and entitled Jerk, Acceleration, and Velocity Limited Position Pattern Generator For An Elevator System is directed to the above type pattern. I

Difficulty has been experiences in defining the initiation of transitions between the maximum acceleration mode or the maximum velocity mode of the control pattern and the maximum deceleration mode. With the control pattern running the instant of slowdown initiation desirably is the last moment at which the pattern can be slowed to the desired stop within the deceleration and jerk constraints. This instant is established only with difficulty. A division of the above Hall et al. Patent entitled Elevator Control which issued as U.S. Pat. No. 3,612,220 on Oct. 12, 1971, discloses means which continuously compute the stopping point for a pattern with fixed jerk, acceleration and velocity constraints and, in response to a coincidence of a signal to stop at a position and the computation of that position point, initiates the patparticularly where high gain servo controls are employed. In the case of the system of Hall et al. instability of components was found to adversely affect the stopping distance computations such that inaccuracies were reflected to the elevator car through the amplification of the controlling signals.

SUMMARY OF THE INVENTION Motion of an object is controlled according to the present invention by predicting its motion at a high repetition rate and sensing the predicted results relative to a desired result. More particularly in the case of an object subject to a pattern signal controlling the object drive, the predictions are made from the current value of the pattern signal and the pattern signal is modified in accordance with the predicted results. As applied to an elevator hoist motor control, a velocity vs. displacement pattern can be idealized for fixed absolute values of jerk; maximum acceleration and maximum velocity by a transition from rest to maximum acceleration with fixed positive jerk, by continued maximum acceleration until a velocity is reached at which the imposition of negative jerk will bring the signal to maximum velocity when zero acceleration is achieved. When the car is to be stopped at a fioor, negative jerk is imposed on the pattern until the negative maximum acceleration is achieved and that deceleration is continued until a velocity from which positive jerk will produce a coincidence of zero acceleration and zero velocity and the car is maintained at rest by removing all jerk from the pattern signal. For example, with a control operating at a maximum velocity of 600 ft./min or 10 ft./sec. with a maximum acceleration of 4 ft./sec. and a jerk of 8ft./sec. the transitions between maximum velocity and maximum acceleration are made with constant jerk at velocities between 9 ft./sec. and 10 ft./sec. and the transistions between zero velocity and maximum acceleration are made with constant jerk at velocities between 0 ft./sec. and l ft./sec.

The acceleration and, if attained, the maximum velocity modes of pattern signal generation are considered an initial phase of operation while the deceleration will be termed the terminal phase of operation. The elevator controlling pattern and thus the elevator are kept in the initial phase until switched to the terminal phase. Effectively a model of the elevator controlling pattern is operated at a rapid repetition rate, such as one thousand times the pattern, to compute the distance the elevator and its controlling pattern will require to stop if it is switched to the terminal phase. Thus, when the fast model, termed the fast plant, predicts that if the controlling pattern, termed the slow plant, were switched to the terminal phase at a given instant it would just reach the target floor, the slow plant is switched to the terminal phase and maintained in the terminal phase until the elevator comes to rest at the target floor.

When a start signal is imposed, the initial phase is initiated. For a full speed run, positive jerk is applied at a value to the slow plant and held until the velocity signal attains its transition value, 9ft./sec. in the example.

This step function is integrated in an integrator having a limiter which limits acceleration at :4 ft./sec so that the acceleration increases from to 4 ft./sec. and then remains Constant. At a velocity of 9 ft./sec. developed by a second integration of the first integrated signal, as detected by a comparator, the jerk is switched to -8 ft./sec. The jerk is held at -8 ft./s'ec. until the acceleration is detected by a comparator to be 0. At that time the jerk signal is eliminated and the elevator should continue to travel at ft./sec. until initiation of the terminal phase.

In the event the slow plant is switchedtg its terminal phase before it is s teered to a velocity signal of 10' ft./sec., the switches controlling jerk are operated at an earlier time. This terminal phase institution is controlled by the fast plant. While ideally the fast plant should have a performance identical to that of the slow plant, in practice, inaccuracies in circuit characteristics and drift in values of components are accommodated by providing it with a performance slightly inferior to that of the slow plant. In the example, its jerk limits and acceleration limits can be set at slightly less than :8 ft./sec. and i4 ft./sec. respectively. Hence, the distance it will take to come to rest is slightly greater than that of the slow plant and the elevator. For example, if jerk is set at 17.5 ft./sec., with ,all other limits at their nominal values the distance it would require to stop from maximum speed is 15.16 ft., while the elevator would require only ft. This slightly impaired fast plant performance enables closed loop control to be used in the terminal control phase.

The fast plant generates a terminal control performance pattern initiated from the instantaneous acceleration and velocity values established by the slow plant. Using these initial conditions, it computes the distance that it would require to stop if the optimal control strategy is used in the terminal phase. When the fast plant predicts that the elevator could just be stopped in the distance remaining to go to the target floor it switches the slow plant to the terminal phase. This overrides the initial phase control to impose a jerk of 8 ft./sec. Since the fast plant has inferior performance and predicts a slightly greater distance to stop than is actually required, the slow plant if allowed to follow its optimal control strategy would reach zero velocity short of the desired floor.

In the terminal phase the fast plant repetitively predicts the position at which the elevator would stop. Hence, when this stop is predicted to be short of the floor of the stop, the jerk signal imposed on the fast plant changes from -8 ft./sec. to +8 ft./sec. This causes the acceleration to increase above -4 ft./sec. until the fast plant again predicts the stop to be beyond the floor of the stop. At this time, the jerk signal is changed from +8 ft./sec. to 8 ft./sec. This cycle is repeated many times until the target floor is reached.

In the discussion which followsit should be understood that the control disclosed is applicable to objects other than elevator cars and to constraints other than those illustrated. The over-all control strategy is effective over a wide range of velocities. The rate of generation of fast plant signals can be altered to greater speed where closer control is desired or lesser speed where looser control is acceptable.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic representation of an elevator system;

FIG. 2 is a graphic representation of the movement of anrelevator with a plot of velocity against time for the optimal control strategy assumed; I

FIG. 3 is a short run version of the plot in FIG. 2;

FIG. .4 is an exaggerated plot of velocity vs. distance to go for the actual control pattern;

FIG. 5 is a block. diagram of one form of .elevator controller and elevator position signal generator according to this invention;

FIG. 6A through 6[ show the logic symbols the schematics;

FIG. 7 is a schematic representation of a system control and a step counter which can be employed in the system of FIG. 5;

FIG. 8 is a logic sequence for FIG. 7;

FIG. 9 is a schematic representation of a floor counter which can be employed in the system of FIG.

FIG. 10 is a schematic representation of a latch. and binary subtractor which can be employed in the system of FIG. 5;

FIG. 11 is a schematic representation of a digital-toanalog converter for developing signals for the system of FIG. 5;

FIG. 12 is a schematic representation of a predicted pattern generator for FIG. 5;

FIG. 13 is a schematic representation of a logic generator and detect logic for a system as in FIG. 5;

FIG. 14 is a logic sequence for FIG. 13;

FIG. 15 is a schematic representation of'a pattern generator for producing a velocity based pattern to a motor control for the system of FIG. 5;

used in FIG. 16 is a schematic representation of a jerk logic,

control for FIG. 5; and

FIG. 17 is a logic sequence for FIG. 16.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 DRIVE CONTROL SYSTEM The drive control system for an elevator is functionally depicted in the block diagram of FIG. 1. In that system, a hoist motor 11, which advantageously from the standpoint of speed control can be a DC. motor having a separately energized shunt field winding and an armature supplied for speed control from a variable voltage source, drives an elevator car 12. Car 12 is counterweighted as at 13 to compensate for some suitable portion of the rated load of the car, ordinarily 40 percent of rated load, whereby the car is fully counter-balanced when loaded to 40 percent of capacity, is less than counterbalanced when loaded in excess of 40 percent, and is overbalanced when loaded to less than 40 percent of rated capacity. Control of hoist motor speed is determined from a variable voltage source 14 which in the discussion to follow will be a direct current generator having its armature driven from a suitable prime mover at a constant speed and its shunt field current varied to control the voltage it applies to the motor armature, in accordance with well known Ward-Leonard principles. The shunt field of the generator may be supplied from any suitable source as for example a group of silicon controlled rectifiers having phase control firing circuits which may be of the general type disclosed in US. Pat. No. 3,593,077 which issued July 13, 1971, to Richard C. Loshbough entitled Electrical Circuit for Pulse Fed Inductive Load. Control of the firing circuits or other mechanism for establishing the current flow in the shunt field of the generator is afforded by a velocity control unit 15. The velocity control unit receives its signals from the elevator controller 16. The drive controller signals are produced from car position, car speed, direction of travel, and target floor data. Car position data can be obtained digitally as through an up-down counter activated by the rotational motion of the elevator drive sheave. Pulses generated in given sequences can signify direction of travel and displacement, conveniently in increments of 0.01 ft. Correction for missed count, falsecount and cable stretch or slip can be superimposed on the count of the counter from a set of vanes at each floor which produce a binary code strobed each time a floor is passed. Target floor data is produced from a call selector whose function is to ascertain the location of landings along the path of travel of the elevator at which service is required by the elevator.

The drive control is a computer which continuously generates repetitive predictions of where the elevator would stop if slowdown were initiated at that particular time during its travel. If the stopping point coincides with the target fioor, the slowdown is initiated with the proper output to the velocity control unit.

Before considering the elevator controller, a general discussion of the dynamics of-theelevator will be considered. A primary consideration in this presentation is the comfort and safety of human beings conveyed by the moving equipment. Therefore, certain limitations must be imposed upon the movement of the elevator.

The minimum time of point to point operation would take place at a maximum constant velocity. However, this could not be tolerated since the initiation and termination of the motion desired would require infinite acceleration. Therefore, a transition should include a period of acceleration at the initiation of motion and deceleration at the termination of motion. Passenger comfort dictates that acceleration must not exceed somelimits. In elevator applications four feet per second per second is considered quite acceptable.

With a finite and constant acceleration, however, the rate of change of acceleration or jerk" at the initiation and termination of the acceleration periods would be infinite. Accordingly, a further constraint is that the rate of change of acceleration must be finite and not exceed a stated limit. A rate of eight feet per second is acceptable for elevator applications.

In elevator utilizations excellent riding characteristics can be achieved by employing constant jerk or rate of change of acceleration from zero speed through a transition period to a period of constant acceleration until the maximum velocity is approached, at which point a constant negative rate of change of acceleration is utilized to enter the constant maximum velocity portion of the run. Once full speed has been attained, it is maintained untilit is appropriate to initiate the slowdown by a transition to a constant negative rate of change of acceleration to constant negative acceleration which continues until zero speed is approached at which time there is a transition to a positive rate of FIG. 2 ELEVATOR VELOCITY VS. TIME If we look at FIG. 2 we can see that period t t, is constant positive rate of change of acceleration, period t t is constant positive acceleration, period t t: is constant negative rate, of change of acceleration, period t L is constant maximum velocity, period t, I is constant negative rate of change of acceleration, period t I is constant negative acceleration and period t t, is constant positive rate of change of acceleration. FIG. 3 shows a similar run where the maximum constant speed was not attained, hence the t I interval is absent and all other intervals correspond to FIG. 2.

If we consider the system constraints from a mathematical point of view in terms of displacement, it can be seen that velocity is the first derivative of displacement with respect to time, acceleration is the second derivative of displacement with respect to time and rate of change of acceleration or jerk is the third derivative of displacement with respect to time. If constraints or finite limits are imposed on a jerk signal; an integration of the jerk curve with respect to time undertaken subject to scaled acceleration constraints produces an acceleration curve subject to the acceleration and jerk constraints. An integration of the jerk and acceleration constrained acceleration curve if subject to scaled limits of velocity then produces a velocity curve subject to the velocity, acceleration and jerk constraints.

A third integration yields a displacement vs. time function with it again meeting the constraints of jerk, acceleration and velocity. This method of simulating the movement of the elevator provides the basis for the elevator controller.

The velocity vs. time curves of FIGS. 2 and 3 are produced by the pattern generator. Inside each of these velocity envelopes is a series of stopping curves. These curves are continuously being produced by the predicted pattern generator from the acceleration, velocity and distance to target information. When the displacement represented by the area under one of these curves coincides with the distance to a target floor at FIG. 4 VELOCITY VS. DISPLACEMENT.

In the logic of control employed here transitions in the operations are undertaken at predetermined displacement, velocity, and acceleration values and relationships. One such predicted relationship is the displacement to the current destination of the elevator, defined as the next landing at which it can be stopped from its current state of acceleration and velocity. In this regard it should be noted that predicted acceleration, velocity and displacement are treated as corresponding on a time base to actual elevator car acceleration, velocity and displacement even though some lag of the car relative to the pattern is actually experienced.

Car and pattern slowdown are initiated when it is predicted by the fast plant that the car can be brought to a stop from its current position velocity and acceleration at a destination or target floor h, for which a stop is required. Viewed in another manner this stop initiation point is defined when predicted displacement A from the current velocity and acceleration conditions equals the current position less the target floorposition 11-11,. FIG. 4 shows a family of curves of velocity vs. displacement as generated by the fast plant and corresponding to pattern for the slow plant and the car. When the abcissa of the predicted curve corresponds to the target floor h, at zero velocity and a stop is required at that floor, the fast plant signals the slow plant controls to initiate a slowdown as from point A of the slow plant. The slow plant begins a deceleration pattern as generally shown at A-h, and is corrected when the fast plant predicts from various points along A-h, that it has deviated from a path which will bring it to h, at the moment it attains zero velocity.

Critical points on the curves of FIG. 2, 3 and 4 will be considered with respect to the predictive control operation. Included in these considerations will be short runs where maximum velocity is not attained as where slowdown is initiated along the portion -5 of the curve of FIG. 4, and the factors establishing transitions in control as at times t t t and t, of FIGS. 2 and 3.

FIG. 5 ELEVATOR CONTROLLER Since the pattern control is by imposition of step function jerk signals either as a positive jerk to increase acceleration, a negative jerk to decrease acceleration, or a hold signal of no jerk where no change in velocity is desired, the system is directed to the control of jerk signals from a control section termed jerk logic 39 to the pattern generator or slow plant" 41. The transitional states for the pattern are thus translated in the jerk logic 39 as a car start signal, a terminate maximum acceleration signal, an stopping initiate stopping signal and a terminate maximum deceleration signal. I

Car start and direction of start signals are developed in that portion auxiliary to the system governing the location of the car in response to s service requirements such as hall calls, car calls or parking signals (none of which is shown). The terminate maximum acceleration" signal is developed during acceleration at t of FIGS. 2 and 3 when the velocity signal 11' of the slow plant 41 has reached a value from which it can make a smooth transition at the negative jerk value to the maximum value. Initiate stopping signals are issued at time t of FIG. 2, at time 1 of FIG. 3, and at position A of FIG. 4, when the distance the car has to go (h--h,) equals the calculated slowdown distance for the instantaneous state of the car as dictated by the pattern. Accordingly, the locations of the car, h, and of target floor, h,, are ascertained and the difference is compared with the predicted slowdown distance.

In the illustrated embodiment the transitions from maximum acceleration to zero acceleration as the pattern enters the maximum velocity condition at time 1 r of FIG. 2 and as it enters the zero velocity condition at time 2,, t, of FIGS. 2 and 3 is dictated by velocity. Pattern velocity is sensed for this purpose and actuates transitional signals at critical velocity values.

Position signals are developed in control 17 and are utilized with car start, car direction and car stop data, from sources not shown, in the control 18 for a velocity based pattern generator represented in FIG. 5.

The position signal generator 17 is considered in greater detail in the aforenoted Edward 0. Gilbert et al.

patent application. It comprises a plurality of signal generators such as magnetic reed switches (not shown) mounted on the car 12 which are responsive in binary code combinations to the positioning of the car 12 at check points along the cars path of travel. Such response can be controlled by vanes (not shown) of ferromagnetic material critically positioned in the hatchway for the car. Advantageously, the check points are coincident with landings for the floors served by the car and the signal generators are enabled only in a narrow range of travel at the floor, for example, over 0.01 foot centered on the landing. The floor position of the car is indicated by a six bit binary code from 19 both during its travel past landings and while stopped at each landing. Thus, a home station signal is established for a stopped car and a check of car travel is provided during each trip.

Car travel is also indicated from a pulse generator 21 which generates a pulse for each 0.01 foot increment of travel. Car position countof the pulses from 21 are accumulated in up-down counter 22 in a seventeen bit binary code. This count is periodically checked by decoding the car floor position code from 19 to the position code of counter 22. When the car passes a check point, a signal from 19 actuates priority control 23 to a position check mode wherein the six bit binary code is passed to binary to lines decoder 24 having a line output for each floor served by the car. The line output is translated to the seventeen bit binary code of the counter at the count assigned the check point or landing position in a' line to binary position decoder 25. The count of the floor position is imposed as a check and, if necessary, count reset on the counter 22 through data sets 26 enabled by priority control 23.

The position count of up-down counter 22 is applied to a latch and binary subtractor 27 of the controller 18 as a seventeen bit binary code signal representing car position 11. Position signal generator 17 also supplies the target floor position to the latch and binary subtractor 27 in the seventeen bit binary code signal representing target floor position h,.

Controller 18 identifies the current target floor for position signal generator 17 on input 28. The signals on input 28 are in the six bit binary floor code of 19 and are translated to the seventeen bit binary position code by the decoders 24 and 25 under the target floor mode of operation of priority control 23. A floor data request on 28 institutes the target floor mode in 23 to pass the target floor signal to decoders 24 and 25 and to enable data sets 29 to pass the target position signal on input 31 to latch and binary subtractor 27.

Position signal generator 17 also establishes the initial floor for each trip of the 'car as utilized in floor counter 32 of controller 18. Whenthe car is at rest, a floor data request signal from floor counter 32 is applied to priority control 23 while the floor position of the car is indicated from 19, the resultant six bit floor code is passed on input 33 to floor counter 32 to identify the floor from which the next car run will take place.

Controller 18 identifies the target floor in floor counter 32. Counter 32 advances the floor count in the direction of car travel indicated, up on lead 34 and down" on lead 35, in response to a step signal from step counter 36. When the car is issued a start signal as on input 37 step counter 36 advances floor counter 32 to the next floor in the direction of travel.

As the car advances in its travel to the location from which it can no longer stop at the current target floor in step counter 32, considering its state of acceleration, velocity and displacement, and its constraining limits of jerk, acceleration and velocity, system control 38 causes the step counter 36 to advance the floor counter 32 provided no stop signal is imposed for the current target floor. If a stop signal is present, the jerk logic control 39 is placed in its negative jerk mode by a signal from system control 38 to initiate slowdown of the pattern from slow plant 41. Y

The decision to initiate a stop is based upon the predictions of the displacement of the car to a stop from its current pattern position and pattern condition being equal to the distancebetween the actual car position and its destination. That distance is calculated as a binary number in latch and binary subtractor 27 after the system control reads a target floor address into 27 together with car travel direction and the car position indicated by up-down counter 22. The digitally defined distance is converted by digital-to-analog converter 42 to an analog signal for comparison with predicted displacement to a stop as developed in the predicted pattern generator or fast plant 43.

Fast plant 43 repetitively generates a velocity and displacemnt signal utilizing, as a starting point for the generation, the acceleration and velocity signal then present in the slow plant. 41 as applied over input 44. Control of the cycling of the fast plant is by logic generator 45. Fast plant 43 transmits a signal on input 46 indicating that predicted displacement has been calculated and predicted velocity is zero. Logic generator response to the zero velocity by recycling fast plant 43 by means of an enabling signal on input 47.

When the fast plant velocity is zero and the predicted displacement equals the distance to go to a destination, detector 48 causes the jerk logic control 39 to impose negative jerk on slow plant 41.

If we assume the elevator is at rest, we then apply a car start signal to line 37 by initiating a call at any floor. This start signal plus an enabling signal from system control 38 tells the step counter'36to advance the floor counter 32 to one floor above (or below) the current floor, depending upon the direction of the start initiating call from the car, and designates that floor the current target floor. This action enables the elevator controller to consider the need for a stop at the target floor. The target floor position is in the form of a 6-bit address. When requested by system control, the position signal generator 17 reads the 6-bit address, converts it to a 17-bit binary floor position in which each binary l hundredth foot. This target floor position h, is then transmitted to the latch and binary subtractor 27. At the same. time 17-bit information on present car position is also transmitted from up-down counter 22. They are combined to provide distance to target floor data which is converted to a voltage, by the digital-to-analog converter 42. Also, system control 18 transmits a signal to the jerk logic 39 which initiates positive jerk on the pattern generator or slow plant 41. The pattern generator simulates the pattern of the elevator velocity as depicted in FIGS. 2 and 3 and transmits a voltage proportional to velocity to the velocity control unit 15.

The predicted pattern generator or fast plant 43 predicts where the elevator would stop if a slowdown signal were given at that instant. It runs at a speed will denote a displacement of one one- 1,000 times faster than the pattern generator. The predicted pattern generator receivescurrent velocity and acceleration values from the pattern generator to use as initial conditions for each calculation. When the predicted stopping pointli equals the target distance to go (h-h.) and predicted velocity is zero (I i 0) as detected by the detect logic 48, then the system control checks to see if there is a call for that floor. If there is no signal on the car start line 37, then the slow plant 41 will initiate a car stopping operation and the car will stop. If there is a signal on the car start line to indicate no stoppingrequirement at that floor, then the system control 38 signals the step counter 36 to advance one floor and this becomes the new target floor. The logic generator 45 generates the signals to cycle the predicted pattern generator 43.

FIG. 6 LOGIC SYMBOLS FIGS. 6a through 6i are logic symbols which are used in the system schematics. Lines entering the left sides of these symbols are all input lines and lines coming from the right sides are all output lines. FIG. 6a shows an inverter. The output of this gate is the complement of the input. For example an input of logic l becomes an output of logic 0. This is also called a NOT gate. 7

FIG. 6b is an exclusive OR gate. If both inputs are the same, the output is 0. If the inputs are different, the output is 1 FIG. 6c is a NOR gate. If both inputs are 0 the output is 1. Any other combination of inputs produces an output of 03 FIG. 6d is the sysmbol for a NOR gate in negative logic. v i

FIG. 6 e is the'sym bol for a NAND gate. If both inputs are l the output is "0." Any other combination of inputs produces an output of l FIG. 6f is the symbol for a NAND gate in negative logici FIG. 6g is the symbol for a .l-K flip flop. The output at Q is the complement of the output ME. A reset pulse at R, a O, overrides the clock C and always produces a 0 output at Q. A 0" at .I and K with a clock pulse at C leaves Qat'whatever it was before the clock pulse. A 0.at J and A 1 at K with a clock pulse produce a 0 output at Q. A 1 at J and a 0 at K, as shown for 315 and 316 of FIG. 16, with a clock pulse produce a 1 output at Q. A l at both J and K with a clock pulse produce the complement at Q of whatever it was before the clock pulse.

FIG. 6h is a NOR gate flip flop. If both inputs are l both outputs are at O. If input No. l is 1 and input No. 2 is 0 then output No. 3 is .O and output No. 4 is 1. If input No. l is O and input No. 2 is 1 then output No. 3 is 1 and output No. 4 is 0. If both inputs are 0 then the output will depend upon the previous state of the flip flop and which NOR processes its input signal first but the outputs No. 3 and No. 4 will always be complements.

FIG. 6i is a NAND gate flipflop.,lf both inputs are 0 then both outputs are at l If the input to No. l is 0" and the input to No. 2 is 1 then the output at No. 3 is l and the output at-No. 4 is 0. If the input to No. l is I and the input to No. 2 is 0 then the output at No. 3 is 0 and the output at No. 4 is 1. If both inputs are l then the output will depend upon the previous state of the flip flop and which NAND processes its signal first but the outputs No. 3 and No. 4 will be complements.

FIGS. 7 AND a SYSTEM coNTRoL AND STEP COUNTER a position spaced a distance from the target floor whi h V is equal to the predicted slowdown distance (hh, on leads 53 and 54 as a transfer to a l and a respectively as actuated in detector 48. If at the moment (h-h', no stop signal is registered for the current target floor, the system control permits the target floor to be advanced. If a stop signal is registered at that moment it inhibits further advance of the target floor and resets its elements for a new run.

Logic is contained in the system control 38 to activate jerk logic 39 and slow plant or pattern generator 41 through imposition of a 1" on lead 51 after the floor counter 32 has been advanced from the home station to designate the next floor as the target floor and that data setting forth the position of the new target floor has been requested and read into the latch and binary subtractor 27. Fast plant displacement to zero velocity calculated and predicted in the fast plant 43 and compared with the distance to the target floor is used by the system control on leads 53 and 54 to remove a start stopping signal to the jerk logic 39 on lead 55 if no stop is imposed for that target floor. The'absence of a start stopping signal is a 0" on 55. Those.conditions also reset the system control internally. v

A run of several floors requires advance of the target floor as the car passes the position from which it can last make a stop at the current target floor.Thus system control responds to an (hh,' signal by advancing the target floor to the next floor in the direction of travel. A stop to the next floor signal, a l on lead 56 to floor counter 32, causes a target advance.

When the car is stopped, system control 38 issues a signal on lead 57 to enable the floor counter 32 to read the true car position from the priority control 23 of the position signal generator. This position signal is derived from floor vanes in the elevator shaft.

When the elevator car is at rest, line 37 is at O. This produces a l signal at line 57 from inverters 58 and 59, and the inversion by NAND 61. The 1 at 57 sets the floor counter 32 with the current floor address of the car in a manner which will be described later. This signal also prevents the step counter 36 from activating. During the following description, refer to logic sequence FIG. 8. When a call is received at t a car start signal in the form of a l appears on line 37. This can be accomplished by the closing of a relay for example. This changes the signal on line 57 to 0" since 93-3 is 1 as will be shown later, and inhibits the preset on the floor counter 32 as shown in FIG. 9. Line 62 goes to 0 at t,, after a delay caused by charging capacitor 63.

Delayed flip flops such as NOR flip flop 64 are employed in several portions of the following description. In discussing these and other multi-terminal elements, a convention will be employed in which the terminals are identified by the device reference character followed by a dash and the terminal designation as 64-1 for the first terminal of flip flop 64.

Initially lead 57 is a 1 and flip flop 64 receives a 0" on 64-1 and a l on 64-2. When the 0 appears on 57 it makes 64-2 0" immediately to make a 64-4 a l with no immediate effect at 64-3. However, when the delay of capacitor 63 expires, the 0" inverted by inverter 65 to a l at 64-1 makes 64-3 :1 0" thereby applying the delayed O to lead 62. Line 56 has been at 0 during this time, but when 64-3 goes to 0" the l issued by inverter 66 is delayed at 67 while capacitor 68 chargesfrom the change to l During this delay, a l pulse is'produced at line 56 by the coincidence of the residual 0" on 69-1 of NOR 69 and the newly applied "0 on 69-2 from junction 62. This pulse steps the floor counter 32 to the next floor which is now target floor by enabling direction signals to add or subtract one floor from the current car position and thereby provide the six bit binary code for the next floor.

After the floor counter 32 is advanced, its six bit bi.-

nary floor designation is translated to the seventeen bit binary position designation so that the latch and binary subtractor 27 can operate on that position in calculat- .ing h-h, or the distance between the. car and target floor.

The 0 at 57 resulting from a car start signal next causes NOR flip flop 71 to transfer states. This follows the transfer of 64 because of the greater delay introduced by capacitor 72 than that introduced by capacitor 63. The residual 0 at 71-1 is coincident with the sustained 0 from 71-4 even as 71-2 goes to 0 until. the delay expires and 71-1 goes to 1 making 71-3 0. At that time t,, 71-4 goes to l." The 1 from 71-4 is applied to 73-2 of NAND 73 to make lead 74 0. This is the request data signal which enables NOR gates 75 of floor counter 32 in FIG. 9 to impose a six bit binary coded new target floor address from leads 76 on the priority control 23.

Termination of the request data signal is by the NOR flip flop 77 delayed by capacitor 78. 71-3 in going to O initially imposes a 0 on 77-2 to make 77-4 l After the delay of capacitor 78, 77-1 also goes l to make 77-3 0 at t and 73-1 0. This makes 73-3 l to terminate the request data signal at 74.

During the interval of the request data pulse the floor position data is issued by decoders 24 and 25 and data sets 29 over the input 31 to latch and binary subtractors 27. The logic pulse from flip flop 71 at 71-4 produces a change of state in the output 79-3 at t of NOR flip flop 79 with a delayed change in the output 81-3 of NOR flip flop 81 to produce a pulse at the output 82-3 of NAND 82. This read data pulse is transmitted to the latch and binary subtractor 27 by line 52 to read the target floor position. The pulse will tell the latch and binary subtractor 27 to read the address of the target floor as encoded to a 17 line digital signal by decoders 24 and 25 and data sets 29.

At the end of the request for data pulse (FIG. 8 on lead 74) t when the output returns to l a short 0 pulse is generated on line 83 and the output 84-4 on line 51 from NOR flip flop 84 changes from 0 to l This pulse is transmitted to the jerk logic 39 and the pattern generator 41. Line 85 is a full stop signal from the jerk logic 39 and the output on line 86 goes to the preset input of floor counter 32 to inhibit the preset for runs of more than one floor when the state of NAND 61 is shifted to advnace the target floor.

When the run of the car is for more than one floor the car start signal will remain l as h-h,=h and an advance target floor pulse will issue as a l on lead 56 at t,, followed by a request data interval of a 0" on lead 74 at t and in that interval a read data" interval of a on lead 52 at t The initiating advance target floor signal results from the transition of 61-2 from 0 to 1.

When h-hr-h lead 54 goes 0" while the car start signal holds a 0 on line 87, NOR 88 is gated to issue a l to 89-2 of NOR flip flop 89 at t. which issues a 0" at 89-4 to NOR flip flop 91 delayed by capacitor 92. NAND 93 receives a 1 from 91-3 at t, after the delay of capacitor 92 to gate a 0 from 93-3 to 61-2. With the assumed car start I coincident at 61-1 an advance target floor cycle is instituted by the 1 issued at 61-3.

The 1 from 91-3 resets the advance target floor instituting signal of NAND 61 after a delay determined by capacitor 94 and the issue ofa 1 by 95-4 of NOR flip flop 95 to 93-2. 7

After the advance target floor cycle is instituted, flp flop 89 is reset. The onset of the request target data signal, a O at 73-3, is passed on lead 96 to 97-1 of NAND 97 as a pulse by coupling capacitor 98. Positive bias on lead 99 imposes a 1 on 97-2 whereby a l is issued from 97-3 to 89-1 to resetflip flop 89. A similar reset of flip flop 89 occurs when the car start signal is removed and coupling capacitor 101 in lead 99 imposes a 0 pulse on 97-2.

As each target advance cycle institutes a read data" function, NAND 82 provides a reset pulse 0" on lead 102 passed by coupling capacitor 103 to 104-1 of NAND flip flop 104. This assures that the flip flop 104 will be set with a O at 104-4 to the start stopping signal input to the jerk logic 39 on lead 55. A start stopping signal as a 1" on lead 55 is actuated by a 0 on lead 105 from NAND 106. Each occasion in car travel that a target floor advance is indicated a stop is considered. Lead 53 receives the complement of the signal on lead 54. Thus, when hh,=ii, detector 48 issues a l on lead 53 without effect if the car start signal is present at 37 to maintain a 0 on lead 87. If no car start signal is present as prior to t lead 87 imposes a l on 106-1 so that upon coincidence of a l on 106-2 a 0 is applied to 104-2 to switch lead 55 to a 1" and institute the stopping functions in jerk logic 39. This occurs at (See FIG. 2) and earlier in FIG. 3 where full speed has not been attained.

Lines 85, 108, 109, 111 and 105 come from the inputs to several gates in the system. When switch 112 is closed, these inputs are grounded. This is a means to assure initial conditions when starting up after a complete shutdown of the elvator system. It is shown as a manual switch, but for automatic operation,'it could be an electromagnetic relay or similar device which works off the motor-generator set. The switch is open during operation of the elevator system.

FIG. 9 FLOOR COUNTER Upon a signal from the system control logic, the floor counter 32 accepts the floor address from the position signal generator 17 when the car is stopped. When the car starts, an up or down signal will advance the counter one floor in the direction of travel. This new address is the target floor. When requested by system control, the floor counter then allows the data to be read by the supervisor. Where a run of greater than a single floor is made, the target floor is advanced during each advance cycle dictated by the system control 38.

An up or down signal from the elevator is received on lines 113 or 114 respectively. Since both the up and down lines are held at l by resistor capacitor networks, the up or down signal is initiated by grounding the corresponding input line. NOR flip flop 115 provides a mutually exclusive interlock of the signals to Up NAND 116 or DOWN NAND 117. This would produce a 1 output 115-4 or 115-3 from the NOR attached to that line. It is transmitted to the pattern genera'tor 41 and latch and binary subtractor 27 over line 118 or line 119. The true position of the car or floor address is received asa six bit binary code by the up-down counters 121 over lines 33-2 through 33-2 each for the bit of its suffix, from the priorty control 23 of position signal generator 17 when the car is stopped.

Lines 57 and 86 from stop counte 36 and system control 38 enable the counters to be set only when the car is stopped. When the lines are both at l, the NAND 122 enables the counters to be advanced. When the car is started, a step to next floor 1" pulse from system control 38 on line 56 advances the counter to the next floor by enabling NANDs 116 and 117. When a request data pulse from system control 38 is received on line 74, the target floor address is gated out by NORS 75 on lines 76 to the position signal generator 17.

FIG. 10 LATCH AND BINARY SUBTRACTOR car position information from the shaft of the hoist motor 11 to the binary adder units 124 whose output is the distance the car has to go to the target floor. This output is then sent to the digital-to-analog converter 42.

Target floor position in the form of binary code in which binary 1 represents one one-hundredth of a foot is sent from the data set 29 (FIG. 5) to the latches 123 over the lines 125. The read signal from system control 38 is received on line 52 nd the latches 123 hold the target floor data. A direction signal from the floor counter 32 on line 118 controls a transistor 126, where l is up and 0" is down, and gates the address through twelve Exclusive OR gates 127 (only typical gates being shown) to the four-bit binary full adder units 124.

' The last five bits of car position information are sent by the first and second latches 123 to the digital-toanalog converter 42 on lines 128. The carry from the adder units 124 is sent to the digital-to-analog converter 42 on line 129. A gate signal goes to the digitalto-analog converter 42 on line 131.

The distance to go is the difference between the car position and the targt floor position (h h This is the output of the adder units 124. It is gated through twelve NANDs (only typic al gates being shown) to FET switches 136 whose output is sent to the digital-toanalog converter 42 over lines 137. The gate signal to NANDs 135 is received from the digital-to-analog converter 42 on line 138. i

The Exclusive ORs and the adder units form a l2-bit twos complement adder-subtractor. This combination can add or subtract any two positive or negative numbers. In the present instance, the only concern is with 15 the subtracting of two positive numbers, the target floor (h,) and the car position (h). When the car is going up, the car position is subtracted from the target floor. The target floor data from the latches 123 is gated by the up signal 1" on lead 118 to the adders 124. The car position on lines 132 from the up-down counter 22 of the poisition signal generator is gated by the up signal on lead 119 which causes the outputs of the exclusive ORs 133 to be the complements of the input. If N -(N+1 that is, the complement of a binary number (N) is equal to the negative of the quantity which is that binary number plus one (N+l) then the complement of 2 would be (2+l or 3. In l2-bit binary numbers, the complement of 2 (00 00 0O 00 O0 would be -3 (11 ll 11 11 ll 01). Therefore, the output of the Exclusive ORs 133 is actually the negative of the quantity the car position plus 1. In order to correct for this, a l is introduced at the carry input 130 as constantly maintained positive bias.

If we designate the target floor as A and the car position as B, then we have A B+ 1 =A(B+l l =AB as the output of the adders 124.,ln the case where the car is going down, the signals to-the Exclusive ORs 127 and 133 are reversed and we have A B l -(A +l) B 1 B-A. The target floor is subtracted from the car position. The output of the adders is always a positive number. J

A 1 on line 138 causes the output of each NAND 135 to be the complement of the input on the lines from adders 124. A large difference between target floor and car position means most of the inputs would be at l, and therefore, most of theoutputs to the FET switches 136 would be 0. This would turn the switches on and cause positive output on most of the lines 137 to the digital-to-analog converter 42. For a small difference, the opposite would be true and most of the lines 137 would be at ground.

FIG. 11 DIGITAL-TO-ANALOG CONVERTER The digital-to-analog converter is shown in FIG. 11. The distance to go to the target floor information from the binary subtractor is converted to an analog voltage which is sent to the predicted pattern generator. As was previously stated a l represents one one-hundredth of a foot. The last five bits of position information are used by the digital-to-analog converter. Lne 134 receives an up or down signal from the latch and binary subtractor 27 to gate the Exclusive OR's 141 with the last five bits of car position information on lines 142 from the up-down counter 22 of position signal generator l7.

Line 131 from 27 also receives an up or down signal and gates five Exclusive ORs 143 with the last five bits of target floor position on lines 128. If the car is going up, the output from lines 142 will be the complement of the input. The last five bits of target floor data are received on lines 128 and the carry output from the adder 124 of FIG. 10 which is always I is received on line 129. When the target floor anD car position are less than 40.96 feet apart, the signals on lines 142 and 148 are all 0 and the outputs of adders 144 are 0. This causes the outputs of NORs 145 to be l which causes a 0 output from NAND 146 and a l input to FET switch 147 which would turn it off. When the target floor and 'car position are more than 40.95 feet apart, at least one of the outputs of adders 144 becomes l and at least one of the outputs of NORs 145 becomes 0 which causes the output of the NAND 146 to becomefl" and the input to the FET switch 147 to be 0" which turns it on. The conductive FET saturates the operational amplifier 148 and causes maximum output signals at 149 and 151.

If the car is going down, the signal from lines 128 becomes the complement while those from 142 correspond and the adding process will be the same as it was for the up direction. I

The distance between the target floor and car position is received from the FET switches 136 on lines 137 by the digital-to-analog converter 152 where it is converted to an analog voltage. This analog voltage is fed on leads 153 and 154 to the operatonal amplifier 148 which delivers an output signal proportional to the distance to go to the target to the predicted pattern generator on line 151 and to the final stopping pattern control on line 149. a

As will be discussed and is disclosed in greater detail in the J. Kuhl R. J. Lauer patent application noted above, the final stopping pattern is developed from the velocity signal when the car is a predetermined distance from a stop, e.g. 30 inches. This signal is employed as a base to proportion the velocity pattern signal to zero as the car proceeds from the thirty inch point to a full stop. Alternatively, the final stop is made with positive jerk maintained to make the transition from maximum deceleration to a stop, as shown in the interval t t, of FIGS. 2 and 3.

The final stopping pattern, that portion of the pattern generated by the slow plant 41 and its adjuncts to stop the car level with the target floor, has been of two forms in the presnet invention. One form employs logic to tranfer from the relatively constant deceleration of slowdown subject to the imposition of positive or negative jerk as indicated to the jerk logic 39 by the stopping position predictd by the fast platn 43 and its detector 48 until a position is achieved in the approach from which the pattern will be brought to-zero velocity and zero acceleration at the landing by maintaining posiitive jerk to make the transition from maximum deceleration to a stop, as shown in the interval t t of FIGS. 2 and 3. The other form is disclosed in greater detail in the J. Kuhl R. J. Lauer patent application noted above. It comprises ascertaining pattern velocity at some predetermined displacement from the landing, e.g. 30 inches, and proportioning that velocity to zero over the displacement of the integrating actual car velocity and employing the integrated signal in a signal multiplier as the multiplicand forthe pattern velocity signal. The integrated signal is modified by being offset from zero and is increased in slope by shaping ciruits so that the proportioning factor approaches zero at a rate somewhat in excess of the normal square law asymptotic approach of the integration.

In view of this approach to a final stop, the analog signal at 151 does not take the additional time of the gradual approach to zero velocity in the predicted pattern or fast plant signal. Compensation for the approximation is provided by adjustable resistor 155 which provides an offset to accommodate the absence of the positive jerk transition to zero velocity at the tail of the curves of FIGS. 2 and 3.

FIGURES 12, 13 AND 14 PREDICTED PATTERN GENERATOR AND ITS SEQUENCING CONTROLS FIG. 12 is a schematic representation of the pre- 

1. A control for an object movable between predetermined points along a predetermined path subject to constraints of predetermined values of jerk, predetermined values of acceleration and predetermined values of velocity comprising means issuing a signal which is a function of the current acceleration of said object; means issuing a signal which is a function of the current velocity of said object; means issUing a signal which is a function of the current position of said object; a predictive signal generator adapted during each movement of said object between said points to repetitively generate signals representing the predicted displacement of said object from its current instantaneous condition of motion to a stop subject to constraints of said predetermined values of jerk, said prederermined values of acceleration and said predetermined values of velocity; means to apply said acceleration, velocity and position signals from siad issuing means which are then current to said predictive signal generator at each generation of said signal of predicted displacement to a stop; and means responsive to a signal from said predictive signal generator for controlling said object.
 2. A control according to claim 1 wherein said object is an elevator car and said path is a hatchway for said car.
 3. A control according to claim 1 wherein said predictive generator includes a velocity signal generator for generating a signal correlated with said predicted displacement signal; and means to recycle said predictive signal generator in response to a velocity signal of zero.
 4. A control according to claim 1 including means to produce a signal which is a function of the current instantaneous acceleration of said object; means to produce a signal which is a function of the current instantaneous velocity of said object; and including means to set the initial conditions for each of said predictive signal generator signal generations according to the current instantaneous acceleration and velocity of said object.
 5. A control according to claim 1 including means to degrade at least one constraint of jerk, acceleration or velocity imposed on said predictive signal generator from the corresponding constraint imposed on the motion of said object whereby a predicted displacement to a stop exceeds the minimum displacement of said object when subjected to a maximum stopping effort within its constraints.
 6. A control according to claim 5 wherein said degradation is of the order of ten percent of the corresponding constraint imposed on the motion of the object.
 7. A control according to claim 1 including; means to signal the position of a destination for said object along its path of travel; and means responsive to a predetermined relationship between said object position signal, said destination position signal and said predicted displacement signal to control said object.
 8. A control according to claim 7 wherein object destinations are fixed locations along the path of travel of said object; and including means to advance said current destination for said object to the next adjacent destination along the path of travel in response to said predetermined relationship.
 9. A control according to claim 7 wherein object destinations are fixed locations along the path of travel of said object; including means to call for a stop of said object at a selected destination; and means to initiate a stop of said object in response to the coincidence of a call for a stop at said destination and said predetermined relationship between said object position signal, said destination position signal and said predicted displacement signal.
 10. A control according to claim 1 including means to sense the distance between said object and a destination for said object; and wherein said means for controlling said object is responsive to the relationship of said distance to the predicted displacement.
 11. A control according to claim 10 including means to define the current destination of said object; and means to advance said current destination to the next available destination along the path of said object in response to a predetermined relationship between the distance between said object and the current destination and the predicted displacement.
 12. A control according to claim 11 wherein said predetermined relationship is equality.
 13. A control according to claim 10 including means to offset a signal from said means to sense the distance between said object and a destination and representing said distance to compensate for approximations made in said predictive signal generator.
 14. A control according to claim 1 wherein said means for controlling said object initiates a stopping sequence for said object.
 15. A control for an object movable along a predetermined path comprising a pattern signal generator generating a signal to control motion of said object subject to constraints of fixed values of jerk, maximum values of acceleration and maximum values of velocity; a predictive signal generator repetitively generating signals representing the displacement of said object from its current instantaneous condition of motion to a stop subject to said constraints of fixed values of jerk, maximum values of acceleration and maximum values of velocity; means to recycle said predictive signal generator at a rate of at least hundreds of times the rate of generation of said pattern signal; and means to control said object responsive to said predicted displacement signal.
 16. A control according to claim 15 including means to impose instantaneous conditions of motion of said object on said predictive signal generator at the initiation of each predictive signal generator cycle.
 17. A control according to claim 16 wherein said means to impose instantaneous conditions of motion of said object is said pattern signal generator.
 18. A control according to claim 17 wherein said means generating a signal which is a function of the instantaneous condition of motion issues a pattern signal value of acceleration for said object.
 19. A control according to claim 17 wherein said means generating a signal which is a function of the instantaneous condition of motion issues a pattern signal value of velocity of said object.
 20. A control according to claim 15 including means to control said pattern signal generator in response to the predicted displacement values generated in said predictive signal generator.
 21. A control according to claim 15 including means to generate a signal characteristic of the position of the object along its path of travel; means to generate a signal characteristic of the location of a destination for said object along its path of travel; and means responsive to a predetermined relationship between said object position signal, said destination location signal and said predicted displacement signal to control said pattern signal generator.
 22. A control according to claim 21 including means to sense the distance between said object and a destination for said object; and means to initiate a slowdown pattern signal for said object in response to the relationship of said distance to said predicted displacement.
 23. A control according to claim 22 including means to increase and decrease the rate of slowdown dictated by said slowdown pattern signal for said object in response to the relationship of said distance to said predicted displacement.
 24. A control according to claim 23 wherein said rate of slowdown is increased in response to said predicted displacement being within a predetermined value of said distance, and said rate of slowdown is decreased in response to said predicted displacement being a predetermined amount less than said distance.
 25. A control according to claim 23 including means to maintain a continuous decrease in the rate of slowdown in response to the slowing of said object to a condition of motion wherein the velocity and acceleration have a predetermined relationship.
 26. A control according to claim 25 wherein said predetermined relationship is h + a h + b 0 where a and b are constants, h is velocity and h is acceleration.
 27. A control according to claim 23 including means to sense the location of said object a predetermined distance from said destination; and means to generate a final stopping pattern to control the final stopping motion of said object in reSponse to the positioning of said object at said location.
 28. A control according to claim 21 including means to initiate a slowdown pattern for said object in response to a first predetermined relationship between said object position signal, said destination location signal, and said predicted displacement signal; means effective during said slowdown pattern to increase and decrease the rate of slowdown dictated by said slowdown pattern signal in response to the relationshisp between said object position signal, said destination location signal, and said predicted displacement signal.
 29. A control according to claim 15 including means to sense the distance between said object and a destination for said object; and means to control the pattern signal generator in response to the relationship of said distance to said predicted displacement.
 30. A control according to claim 15 including means to sense a function of velocity of said object at a predetermined fractional value of maximum velocity; and means to initiate a reduction in acceleration by said pattern signal in response to said sensing means.
 31. A control according to claim 15 including means to define as the current destination for said object the next destination along the path of travel of said object at which said object can be stopped within its motion constraints; and means to shift the current destiantion to a next succeeding destination along the path of travel in response to the prediction by said predictive signal generator of a displacement equal to the distance between said object and said current destination.
 32. A control according to claim 31 including means to require a stop of said object at any of a plurality of destinations along the path of travel of said object; and means to inhibit said shift of the current destination when a stop means for said destination is operated and the prediction by said predictive signal generator of a displacement is equal to the distance between said object and said current destination.
 33. In a control for an object movable between predetermined points along a predetermined path subject to constraints of fixed jerk values, maximum acceleration values, and maximum velocity values, means for predicting repetitively during each movement of said object between said points the displacement of the object from its current instantaneous condition of motion to a stop comprising a step signal source scaled to the jerk constraints imposed on said object; a first integrator for said jerk signal to issue predicted acceleration signals limited to define maximum signals scaled to maximum acceleration constraints imposed on said object; a second integrator for said acceleration signals to issue predicted velocity signals limited to define maximum signals scaled to maximum velocity constraints imposed on said object; and a third integrator for said velocity signals to issue predicted displacement signals; said first, second and third integrators generating signals to produce said predicted displacement signal in time intervals which are short relative to the time intervals for movement of said object between said points.
 34. In a control according to claim 33 means to introduce a signal lag between said second and said third integrator.
 35. In a control according to claim 33 means to generate a signal representative of the distance between said object and a destination; and means to compare that signal to said predicted displacement signal.
 36. In a control according to claim 33 including means to detect a predetermined value of predicted velocity from the signal issued by said second integrator.
 37. In a control according to calim 33 wherein said predetermined value of predicted velocity is zero.
 38. In a control according to claim 37, means to terminate the signal integrations in said first, second and third integrators in response to detection of zero predicted velocity by said detector means.
 39. In a control according to claim 38, means to start thE signal integrators an interval following termination of said signal integrations whereby new prediction signals are generated.
 40. In a control according to claim 38 means to couple the jerk, acceleration and velocity signals to ground in response to said terminating means.
 41. In a control according to claim 40 means to decouple said jerk signal from said first integrator, said acceleration signal from said second integrator and said velocity signal from said third integrator in response to said terminating means; means effective an interval following operation of said terminating means to apply a signal which is a function of the instantaneous value of acceleration of said object to said first integrator and a signal which is a function of the instantaneous value of velocity of said object to said second integrator.
 42. In a control according to claim 41 means to generate a signal representative of the distance between said object and a destination; and means to apply said signal representative of the distance between said object and a destination to said third integrator coincident with the application of the instantaneous values of acceleration and velocity to said respective first and second integrators.
 43. In a control according to claim 38 means to decouple said jerk signal from said first integrator, said acceleration signal from said second integrator and said velocity signal from said third integrator in response to said terminating means.
 44. In a control according to claim 33 including means generating a signal which is a function of the instantaneous value of acceleration of said object; and means to apply said instantaneous value of acceleration signal as an initial condition signal for said first integrator.
 45. In a control according to claim 33, means generating a signal which is a function of the instantaneous value of velocity of said object; and means to apply said instantaneous value of velocity as an initial condition signal for said second integrator.
 46. In a control according to claim 33 means to generate a signal representative of the distance between said object and a destination for said object; means to initiate the stopping of said object when said predicted velocity equals zero and said predicted displacement signal equals the signal representative of the distance between said object and a destination for said object.
 47. In a control according to claim 33, means for generating a pattern signal for controlling the motion of said object; and mens responsive to said predicted displacement signal for controlling said pattern generating means.
 48. In a control according to claim 47, means to generate a signal representative of the distance between said object and a destination for said object; and means to initiate the generation of a stopping pattern for said object by said pattern signal generating mens in response to a predetermined relationship between said predicted dsiplacement signal and the signal representative of the distance between said object and a destination for said object.
 49. In a control according to claim 47 means to impose a fixed level of positive jerk on said means for generating a pattern signals; means to impose a fixed level of negative jerk on said means for generating a pattern signal; whereby imposition of said positive jerk tends to accelerate said pattern signal or tends to reduce the deceleration of said pattern signal and imposition of negative jerk tends to reduce the acceleration of said pattern signal or tends to decelerate said pattern signal; and means responsive to said predicted displacement signal for actuating said means to impose jerk on said means for generating a pattern signal.
 50. In a control according to claim 49 means to generate a signal representative of the distance between said object and a destination for said object; means to sense a predetermined relationship between said predicted displacement signal and said signal representing distance between said object and a destinAtion to actuate said negative jerk imposing means to initiate a stopping pattern for said object.
 51. In a control for an object movable along a predetermined path, a pattern signal geneator subject to constraints of fixed values of jerk, maximum values of acceleration and maximum values of velocity to control motion of said object; a step signal source for signals scaled to the jerk constraints imposed on said pattern signal; a first integrator for said jerk signals to issue predicted acceleration signals limited to define maximum signals scaled to maximum acceleration constraints imposed on said pattern signal; a second integrator for said acceleration signals to issue predicted velocity signals limited to define maximum signals scaled to maximum velocity constraints imposed on said pattern signal; and a third integrator for said velocity signals to issue predicted displacement signals, at least one of said jerk and acceleration signal levels being degraded with respect to said pattern signal constraints whereby said predicted displacement exceeds the minimum displacement to a stop of the object controlled by said pattern signal.
 52. A control according to claim 51 including means to generate said predicted signals from instantaneous conditions of motion of said object to a stop repetitively at a rapid rate relative to the rate of generation of said pattern signal.
 53. A control according to claim 52 including means to set initial conditions of acceleration on said first integrator for each predicted signal generation according to the instantaneous acceleration of said pattern signal.
 54. A control according to claim 52 including means to set initial conditions of velocity on said second integrator for each predicted signal generation according to the instantaneous velocity of said pattern signal.
 55. A control according to claim 52 including means to sense the distance between said object and a destination for said object; and means to control the pattern signal generator in response to the relationship of said distance to said predicted displacement from the instantaneous conditions of motion of said object to a stop.
 56. A control according to claim 55 including means for imposing negative jerk on said pattern generator; mens for imposing positive jerk on said pattern signal generator; and means to institute the generation of a stopping pattern from said pattern signal generator by actuating said negative jerk imposing means in response to a predetermined relationship of said distance to said predicted displacement.
 57. A control according to claim 56 including means effective subsequent to the institution of a stopping pattern to actuate said positive jerk imposing means in response to a predicted displacement less than said distance by a predetermined amount; and means effective subsequent to the institution of a stopping pattern to actuate said negative jerk imposing means in response to a predicted displacement equal to said distance.
 58. A control according to claim 56 including means to sense a predetermined relationship between pattern signal velocity and pattern signal acceleration characteristic of a condition of motion of said body from which said body can be brought to a stop by the continuous application of positive jerk to the pattern signal generator; and means responsive to said sensing means to apply and maintain positive jerk on the pattern signal generator until a predetermined pattern signal acceleration is achieved.
 59. A control according to claim 58 wherein said predetermined relationships is h + a h + b 0 where a and b are constants, h is velocity and h is acceleration; and wherein said predetermined pattern signal acceleration is zero.
 60. A control according to claim 56 including means to sense a predetermined velocity for said object; means to generate a final stopping pattern for said object; and means responsive to said sensed predetermined velocity to enable said means to generate a final stopping pattern.
 61. A control according to claim 60 including means to sense the location of said object a predetermined distance from a destination and means to actuate said final stopping pattern means to supersede control of motion of said object by said pattern signal generator.
 62. A pattern generator for an object movable between predetermined points along a predetermined path comprising means to generate a pattern signal; means to institute a stopping pattern for said pattern signal generating means; means to repetitively generate, in time intervals which are short compared with the time interval of movement of said object between said predetermined points, a signal which is representative of a prediction of the displacement of the object from its instantaneous condition to a stop at a destination; means to actuate said predicting means to generate a prediction responsive to completion of a prediction; means to sense a call for a stop at each of a plurality of destinations; means to define the location of the next destination at which said object is currently capable of being stopped along the predetermined path; means to define the position of said object along the pre-determined path; and means responsive to the relationship between said predicted displacement, said location of the next destination and the position of said object to control said pattern signal.
 63. A pattern generator for an object movable between predetermined points along a predetermined path comprising means to generate a pattern signal; means to institute a stopping pattern for said pattern signal generating means; means to repetitively generate, in time intervals which are short compared with the time interval of movement of said object between said predetermined points, a signal which is representative of a prediction of the displacement of the object from its instantaneous condition to a stop at a destination; means to actuate said predicting means to generate a prediction responsive to completion of a prediction; means to sense a call for a stop at each of a plurality of destinations; means responsive to a signal representative of the displacement of the object from a current destination a distance equal to the displacement predicted to stop at said destination and to the absence of a call for a stop at said destination to establish a new destination.
 64. A pattern generator according to claim 63 inclduing means responsive to a signal representative of the displacement of the object from a current destination a distance equal to the displacement predicted to stop at said destination, and to the presence of a call for a stop at said destination to initiate a stopping pattern to said destination.
 65. A pattern generator according to claim 63 including a decoder for destination signals, and means operated subsequent to operation of the means to establish a new destination to operate said decoder whereby the signal from said decoder is issued for said new destination to said means for developing a signal representative of the displacement of the object from its current destination.
 66. A pattern generator according to claim 63 incuding means defining the direction said object is set to run; and means to control said means to establish a new destination to define a new destination displaced from the current object destination in the direction defined by said direction defining means.
 67. A pattern signal generator for an object movable along a predetermined path comprising: means to generate a signal scaled to positive jerk; means to generate a signal scaled to negative jerk; first means to integrate said signals from said jerk signal generating means subject to absolute limits scaled to acceleration; second means to integrate said integrated jerk signal subject to a limit scaled to velocity; first jerk control means to actuate said postiive jerk generator and inhibit said negative jerk generator; second jerk control means to actuAte said negative jerk generator and inhibit said positive jerk generator; third jerk control means to inhibit both said positive and negative jerk control generators simultaneously; and means to actuate said second jerk control means in response to a predetermined velocity signal from said second means.
 68. A pattern signal generator for an object movable along a predetermined path comprising: means to generate a signal scaled to positive jerk; means to generate a signal scaled to negative jerk; first means to integrate said signals from said jerk signal generating means subject to absolute limits scaled to acceleration; second means to integrate said integrated jerk signal subject to a limit scaled to velocity; first jerk control means to actuate said positive jerk generator and inhibit said negative jerk generator; second jerk control means to actuate said negative jerk generator and inhibit said positive jerk generator third jerk control means to inhibit both said positive and negative jerk control generators simultaneously; and means to actuate said third jerk control means in response to a predetermined acceleration signal from said first means.
 69. A pattern signal generator according to claim 68 wehrein said predetermined acceleration signal represents zero acceleration.
 70. A control for an object movable along a predetermined path including means to define each of a plurality of given destinations along said path; means responsive to the presence of said object in a predetermined spatial relationship with each of a plurality of available destinations for said object for issuing a coded signal characteristic of said destination; means to apply a control signal to start and maintain motion of said object; means responsive to the absence of said control signal to enable said means issuing said coded destination whereby said coded destination signal indicates the initial car position for the next application of said control signal.
 71. A control according to claim 70 including means to predict the displacement of said object from its instantaneous condition of motion to a stop; said means responsive to spatial relationship including means responsive to the distance to go between said object and its current destination equaling the predicted displacement of said object from its instantaneous condition of motion to a stop; a destination counter to issue a count signal to define the current destination of said object; and means responsive to coincidence of said equality sensing means and the presence of said control signal to shift the count signal in said destination counter to define a new current destination.
 72. A control according to claim 71 including a first delay means actuated by said coincidence responsive means to shift said counter after a brief predetermined time interval.
 73. A control according to claim 72 including a decoder for said destination counter signals; means gating destination count signals to said decoder; a second delay means actuated by said coincidence responsive means to actuate said gating means to issue a new current destination count signal to said decoder after a predetermined time interval of greater length than that defined by said first delay means.
 74. A control according to claim 73 including a third delay means actuating said decoder an interval subsequent to response of said second delay means.
 75. A control according to claim 74 wherein said third delay means is responsive to said second delay means.
 76. A control according to claim 73 including a first delayed reset means for said shift means to reset said shift means prior to response of said second delay means.
 77. A pattern generator according to claim 74 including a second delayed reset means for said second delay means; and a third delayed reset means for said third delay means said third delayed reset means operating a predetermined interval following said third delay means and prior to said seCond delayed reset means whereby said decoder is actuated during the interval said new current destination count signal is gated.
 78. A pattern generator according to claim 70 including means to inhibit shift of the count signal of said counter in response to the absence of said control signal and a predetermined relationship between said distance and said displacement.
 79. In a control for an object movable along a predetermined path to predetermined target positions the combination of means issuing binary coded signal bits representative of the position of the object along its path; means issuing binary coded signal bits representative of the location of a predetermined target position; an exclusive ORs for each of a plurality of said object position signal bits; an exclusive OR for each of a plurality of said target position signal bits; means for applying signals of opposite polarity to inputs of said object position exclusive ORs and said target position exclusive ORs according to the direction said object is set to move; a binary adder for adding the output signals of said exclusive ORs for said object position and said target position; and means to add one binary count to the sum of the signals of said exclusive ORs for said object position and said target position to produce a binary signals representing the difference between said object position and said target position.
 80. In a control according to claim 79 wherein said object is an elevator car and said target positions are landings for said elevator car; wherein the direction signal applied to the car position exclusive ORs is a logical ''''1'''' for down travel direction and a logical ''''0'''' for up travel direction; and wherein the direction signal applied to the target landing position exclusive ORs is a logical ''''0'''' for down travel direction and a logical ''''1'''' for up travel direction whereby the car position is subtracted from the target landing position for up car travel and the traget landing position is subtracted from the car position for down car travel.
 81. In a control according to claim 79 including means for intermittent transmission of target position signal bits from said means issuing said bits; signal latches coupled to said intermittent transmission means; and means for up dating said latches during selected intervals. 